====GoalSeek====

The **GoalSeek** function is part of the //model// object.

It's used to find the ideal value of one measurement to result in a particular value of another.

For example, you might have made a model that calculates the size of a balloon from a specific pressure of air. 

Using GoalSeek, you can effectively 'reverse' that algorithm and find out how much pressure you need to reach a desired size. 

===Syntax===

//model//.**GoalSeek(**//To Change//**,**//To Watch//**,**//Goal//**)**

===Parameters===

**To Change**: The value you want to calculate and the data point you'd like to change in order to get the //To Watch// value to reach the //Goal//. In the example above, //pressure// is the value we'd like to change.

**To Watch**: The value we're trying to make reach the //Target//. In the example, it would be the balloon size. 

**Goal**: The numeric target - the function returns the value of the //To Change// parameter needed to make the //To Watch// parameter reach this number.

===Adjusting Bounds===

To help the algorithm run more efficiently, you should try to specify a **minvalue** and **maxvalue** to GoalSeek. These should be between the upper and lower possible limits for the value. 

===Notes===

The goal-seeking algorithm runs the model with a variety of different values for //To Change//, narrowing in on the best match of //To Watch// with the //Goal//.

In some cases, it might not be possible to reach an answer. In these cases, it will often return the  //maxvalue// parameter.

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The **GoalSeek** function will only work if the two parameters (//To Change// and //To Watch//) are dependent. A change in first parameter //must// trigger some kind of change in the other.

If the system can't determine a relationship between the two, the function will fail. 
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